The prevalence of obesity in American youth has reached alarming levels. The proportion of obesity among adolescents has tripled in the past three decades with approximately 15% of 6-19 year-olds qualifying as obese. Many believe that time spent with electronic media is at least partly to blame. It is true that children spend more time using electronic media than in any other single free-time activity except for sleep. However, though there is some evidence linking media use to childhood obesity, a deeper understanding of their developmental connections between them has been hindered by a distinct dearth of longitudinal studies which include developmental and contextual information in explanatory models. The objective of this proposal is to elucidate these connections from childhood through adolescence using longitudinal data from a representative US sample of approximately 3,500 children spanning ages 0-18 from the Panel Study of Income Dynamics (PSID) Child Development Supplement (CDS). We draw upon an ecological framework to deepen existing knowledge of the developmental links between media use and childhood obesity. The richness of the CDS data render them uniquely suited for this purpose and allow for considerably stronger and more comprehensive analyses compared to existing data. Three waves of CDS data will be used, including data from 1997 (ages 0-12), 2002 (ages 5-18), and 2007 (ages 10-18). The CDS panel data represents an extraordinary opportunity to further knowledge regarding the nature of the relationship between children's media use and the development of obesity. Despite over 30 years worth of research efforts aimed at understanding childhood obesity, we know surprisingly little about role of electronic media. Developmental connections have gone unexamined, moderating influences have not been identified, and mediating processes have gone untested. It seems safe to say that technology is here to stay, and is virtually guaranteed to play an ever increasing role in our daily lives. Thus, a thorough understanding of the nature of its impact on the development of obesity is a vital component of the public health agenda in the U.S.